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The scattering of a high frequency photon after interaction with a charged particle at rest (stationary), generally an electron is described by the Compton Scattering.

The wavelength change due to the scattering is given as,

$\mathit{λ}\mathbf{\text{'}}\mathbf{-}\mathit{λ}\mathbf{=}\frac{\mathbf{h}}{\mathbf{m}\mathbf{c}}\left(1-cos\mathrm{ϕ}\right)$ ...(i)

Where, $\mathrm{λ}\text{'}$is the scattered photon wavelength, $\mathrm{λ}$is the wavelength of the incident photon $\mathrm{ϕ}$is the scattering angle.

The concept of Compton Scattering is same for protons as well as electrons. The high energy photon makes a head on collision with a stationary charged particle, proton or electron and loses some of its energy to scatter at an angle denoted by $\mathrm{Ï•}$. The reduced or lost energy is then gained by the particle at rest and it recoils.

There is a different in the wavelength of the scattered photon as according to equation (i) it depends on the mass of the particle the photon is colliding with. As electron’s mass is smaller than that of proton, the maximum energy lost by the photon when colliding with electron is higher than in case of proton.